An adaptive kernel-split quadrature method for parameter-dependent layer potentials
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Panel-based, kernel-split quadrature is currently one of the most efficient methods available for accurate evaluation of singular and nearly singular layer potentials in two dimensions. However, it can fail completely for the layer potentials belonging to the modified Helmholtz, biharmonic and Stokes equations. These equations depend on a parameter, denoted α, and kernel-split quadrature loses its accuracy rapidly when this parameter grows beyond a certain threshold. The present report describes an algorithm that remedies this problem, using per-target adaptive sampling of the source geometry. The refinement is carried out through recursive bisection, with a carefully selected rule set. This maintains accuracy for a wide range of α, at an increased cost that scales as α. Using this algorithm allows kernel-split quadrature to be both accurate and efficient for a much wider range of problems than previously possible.
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